This kind of multi-chamber type manufacturing apparatus is comprised, for example, as shown in FIG. 16.
In FIG. 16, around the periphery of a transfer chamber 2 wherein a wafer carrying robot 1 is disposed are provided process chambers 3a to 3e which implement various types of semiconductor processes on wafers, a work carry in chamber 4 that carries in the work from an external location, and a work carry out chamber 5 that carries out the work to an external location.
Adjustable open/close gate valves 6a to 6g are disposed between process chambers 3a to 3e and transfer chamber 2, between transfer chamber 2 and work carry in chamber 4, and between transfer chamber 2 and work carry out chamber 5. By means of opening these gate valves 6a to 6g, each chamber is made to connect. Further, transfer chamber 2, process chambers 3a to 3e, work carry in chamber 4 and work carry out chamber 5 are maintained in a vacuum state. Further, the degree of vacuum is made to grow larger in order from work carry in chamber 4 and work carry out chamber 5.fwdarw.transfer chamber 2.fwdarw.process chambers 3a to 3e. Gate valves 6a to 6g are restricted in that two or more gate valves cannot be opened simultaneously in order to maintain the degree of vacuum. In other words, when one gate valve opens, opening control of required gate valves starts in a state in which all the other gate valves are closed.
Moreover, a work carry in robot 9 and a work carry out robot 10 are disposed on a work carry in station 7 and a work carry out station 8, respectively. Work carry in station 7 and work carry out station 8 are disposed adjacent to work carry in chamber 4 and work carry out chamber 5. These work carry in robot 9 and work carry out robot 10 implement a carry in and a carry out of the work (wafer) between the carrying system and an external location. In addition, the region on side A in FIG. 16 is an unmanned region and the region on side B is a manned clean room.
In contrast, as shown in FIG. 17, wafer carrying robot 1 disposed in transfer chamber 2 is, for example, a so-called frog-leg type robot comprised by two arms 11, 12 which have a rotation degree of freedom, and a hand 13 shaped like a platform. A wafer detection sensor (not shown in figure) is housed within hand 13. This wafer detection sensor detects whether a wafer W is loaded. Further, wafer W is supported by a lifter (not shown in figure) that can rise and fall. When wafer W loads onto hand 13 of robot 1, the lifter falls.
In this composition, the procedure when wafer carrying robot 1 transfers wafer W from process chamber 3c to process chamber 3d is shown below.
At first, when the lifter that is supporting wafer W within process chamber 3c is lowered and wafer W is loaded onto hand 13 of wafer carrying robot 1 (FIG. 17 point P1), the wafer detection sensor housed within hand 13 turns ON. When this ON state is confirmed, robot 1 tightens arms 11, 12 and wafer W moves to point P2. Then, when wafer W completes the move to point P2, robot 1 stops at this point P2 once and then outputs a withdrawal completion signal to a system controller (not shown in figure) that controls the entire system.
When the above-mentioned withdrawal completion signal is received in the system controller, control starts to close gate valve 6c, Thereafter, when the system controller confirms the closure of gate valve 6c, control executes to open gate valve 6d. In addition, gate valve 6d is made to open after gate valve 6c closes due to the above-mentioned restriction in which two or more gate valves cannot open simultaneously during the open/closing of gate valves 6c, 6d.
In contrast, when robot 1 outputs a withdrawal completion signal to the system controller, the open/close action of gate valves 6c, 6d occurs side-by-side and the robot moves from point P2 to point P3. When point P3 is reached, the procedure stops once again. Then, after robot 1 confirms the open/close state of gate valve 6d at the time when movement stops at point P3 and then confirms the opening of gate valve 6d, movement to point P4 starts. In other words, robot 1 waits at point P3 until the opening of gate valve 6d can be confirmed.
During the movement to point P4, robot 1 extends arms 11, 12 to position P4 where wafer W of process chamber 3d should be loaded and then after a positioning stop occurs at position P4, the robot outputs a movement completion signal to the system controller.
The system controller that received the movement completion signal raises the lifter of process chamber 3d and then loads wafer W onto the lifter from the hand of robot 1. The procedure above is the chain of events in a wafer carrying action.
FIG. 8(a), FIG. 9(a) and FIG. 10(a) show each type of movement speed pattern according to the above-mentioned conventional technology.
Furthermore, in these figures, T is the time (fixed time characteristic to system) required from when gate valve 6c starts to open until gate valve 6d completes the close. This is common to all gate valves.
As is clear from FIG. 8(a), FIG. 9(a) and FIG. 10(a), according to the above-mentioned conventional technology, the robot always stops once at the withdrawal point (P2) from the movement origin process chamber and at the entrance point (P3) toward the transfer destination process chamber. Because of this, time is required for wafer carrying making it impossible to achieve efficient wafer carrying and in addition the throughput (number of processes per unit time) of the process wafer has not improved once at the present.
Thereupon, the temporary stop at above-mentioned points P2 and P3 is simply eliminated. For this case, there are no problems when the distance between the process chambers is sufficiently distant (when the rotation angle is large) although when the distance between the process chambers is short (when the rotation angle is small), if the movement time from point P2 to point P3 becomes shorter than the above-mentioned time T required to open/close the gate valves, the wafer will protrude into the gate valves. Moreover, if this fact is taken into consideration and the robot speed reduced, it will become impossible to determine why the temporary stop at points P2 and P3 is eliminated.
The object of the present invention is to take the above-mentioned points factors into consideration and provide a control device for a work carrying system that can achieve a high-speed work transfer with a transfer speed as short as possible as well as eliminating a temporary stop of the robot as much as possible.